Beta-adrenergic agonists stimulate phospholipid methylation in Hela cells and astrocytomas. Benzodiazapam acid anti-anxiety drugs also stimulate phospholipid methylation in astrocytoma cells. Ca 2 ion ATPase activity is increased after synthesis of phosphatidylcholine is elevated. An association between histamine release in mast cells and phosphatidylserine decarboxylation and phospholipid methylation was observed. Also a close relationship between lymphocyte mitogenesis, phospholipid methylation and arachidonic liberation was found. Chemotactic peptides caused an increased turnover of methylated phospholipids and release of arachidonic acid. Two phospholipid methylating enzymes were found in brain nerve endings.